R/cdss_skill_sa2af.R

In CDSS: Course-Dependent Skill Structures

#' Determine Attribution function for skills from a skill assignment
#' 
#' \code{cdss_skill_sa2af} expects a skill assignment and derives an attribution
#' function on the set of learning objects.
#' 
#' @param sa Skill assignment object
#'
#' @return Object of class \code{kmattributionfunction}
#'
#' @family functions building skill (multi) assignment matrices
#'
#' @export
cdss_skill_sa2af <- function(sa) {
  if (!(inherits(sa, "cdss_sa"))) {
    stop(sprintf("%s must be of class %s.",
                 dQuote("sa"),
                 dQuote("cdss_sa")))
  }
  
  skills <- colnames(sa$taught)
  afcols <- c("Skill", skills)
  af <- data.frame("Skill", t(1:length(skills)))
  colnames(af) <- afcols
  sapply(skills, function(s) {
    teachingrows <- which(sa$taught[,s] == 1)
    if (length(teachingrows) == 0) {
      hf <- data.frame(s, t(rep(0, length(skills))))
      # hf[,s] <- 1
      colnames(hf) <- afcols
      af <<- rbind(af, hf)
    } else {
      sapply(teachingrows, function(lo) {
        required <- sa$required[lo,]
        taught <- sa$taught[lo,]
        # required[s] <- 1
        hf <- data.frame(s, t(required|taught))
        colnames(hf) <- afcols
        af <<- rbind(af, hf)
      })
    }
  })
  class(af) <- unique(c("kmattributionfunction", class(af)))
  af[-1,]
}